It's one of the most commonly prescribed supplements from GPs, but recent research into vitamin D has shown unimpressive results and the jury is still out on whether or not boosting your levels of the 'sunshine vitamin' can benefit the average person’s health.
In the video above a dietitian shows what an ideal day of food should look like to get all your vitamins and nutrients. Watch full episode here.
Chloe*, a 25-year-old doctor working in an Inner-Sydney hospital, has been taking vitamin D every day for almost one year.
After a routine blood test with her GP, she was told that her Vitamin D levels were sub-optimal. While Chloe was only borderline deficient, she decided to err on the side of caution and take the tablets every day.
“I mean, particularly with work, I get there before the sun’s up and I often leave after dark,” she said.
“I think it’s like 10 cents a tablet or so – so I just chuck it into my normal chemist warehouse routine and don’t really think about the cost.”
A Vitamin D deficiency is defined as anywhere under 50 nanomoles per litre and a severe deficiency of 13 nanomoles or less per litre can result in osteomalacia (bone softening).
While many people hold some concern for their Vitamin D levels, it is relatively rare to have levels low enough to be of clinical concern and only seven per cent of the Australian population have a moderate or severe deficiency.
The Vitamin D surge
Vitamin D is one of the most commonly-used dietary supplements by Australians and is believed to have wide-ranging benefits in metropolitan areas where office workers are routinely deprived of its natural source.
Vitamin D is an essential chemical that the body creates when exposed to UV light and its importance in maintaining bone health has long been recognised in the treatment of rickets. In 1928, German chemist Adolf Windaus won a Nobel Prize for establishing the mechanism for Vitamin D production, leading to the fortification of foods with the vitamin and mass reduction in the prevalence of rickets.
The explosive interest in Vitamin D began in the early 2000s after researchers discovered that receptors for the vitamin were found on the majority of cells in the body, indicating that it had fundamental functions beyond the health of bones.
Researchers began to find links between a vast number of diseases and conditions and Vitamin D deficiency including dementia, breast cancer, multiple sclerosis, bowel cancer, cardiovascular disease, schizophrenia, and erectile dysfunction.
As these disease links were established, demand for Vitamin D testing skyrocketed. In Australia, the Medicare expenditure for these serum tests rose from $109 million in 2009-10 to $151 million in 2012-13 and the government was forced to reign in this spending with new policy guidelines in 2014.
The science is still out
Recent studies have indicated that the emphasis on Vitamin D supplements for people like Chloe who do not have a clinical deficiency may be overstated and there is little evidence to support that supplements reduce cancer risk.
These studies suggest that links between Vitamin D and diseases unrelated to bones could well be correlational, rather than causational.
The largest randomized controlled trial on Vitamin D to date, VITAL, came from Brigham and Women’s Hospital in Boston and published its results late last year after studying over 25,000 men and women across the US. The findings were unimpressive: Vitamin D supplementation did not reduce risk of cancer nor the risk of major cardiovascular events such as heart attack or stroke.
To be honest I’m not going to spend 20 minutes to 60 minutes in the sun every day, like that’s just not feasible for me.
Doctor JoAnn Manson, a lead researcher on VITAL stated that while a daily Vitamin D dose doesn’t appear to have any side effects, “the results do not strongly support the initiation of high-dose Vitamin D for prevention of cancer or cardiovascular disease in healthy patients”.
Associate Professor Rachel Neale is a cancer aetiology researcher from the QIMR Berghofer Institute currently leading the world’s second-largest study into the health benefits of Vitamin D, known as the D-Health Trial.
D-Health is trying to establish whether or not taking Vitamin D supplements has health benefits.
“The problem is that people with low Vitamin D also tend to be fairly inactive, thye’re often unwell, so they’re not going outdoors because they’re sick. So Vitamin D actually might be a marker of lifestyle or health and not causing the subsequent risk of disease,” she said.
Neale said that while people with Vitamin D levels of less than 30 nanomoles per litre should absolutely take supplements, the evidence is simply not there yet to support the general population doing the same.
“For the rest of us who are reasonably active, going about our daily business, we get a bit of sunshine – even if it’s not a lot we don’t need a huge amount to make Vitamin D … and at this point in time I don’t believe we need supplementing,” said Neale.
However, Professor Elina Hypponen, Director of the Australian Centre for Precision Health at the University of South Australia Cancer Research Institute believes that taking a cautionary approach to Vitamin D deficiency and using supplements is a justifiable practice for anybody who feels that they do not get enough sunlight.
“If we start moving away from those natural synthesis scenarios, then Vitamin D supplementation is totally appropriate,” she said.
Neale notes that there are high-risk people in the population who could certainly benefit from taking Vitamin D beyond those who are stuck in an office all day, including people who cover their bodies for religious or cultural reasons, who are household-bound for medical reasons or who have darker skin.
Due to Chloe’s dark complexion (she is half Ghanaian) her skin has a reduced ability to synthesise Vitamin D and she feels as though she can’t feasibly allocate the time outside of the hospital to sit and absorb sunlight, despite maintaining some scepticism about the tablets.
“To be honest I’m not going to spend 20 minutes to 60 minutes in the sun every day, like that’s just not feasible for me. So given the fact that it’s not really a hassle for me to take I’m happy to continue supplementation even if there is the correlation versus causation argument.”